diff --git a/src/mergerfs.cpp b/src/mergerfs.cpp
index 64d837d6..2221246b 100644
--- a/src/mergerfs.cpp
+++ b/src/mergerfs.cpp
@@ -395,6 +395,7 @@ main(int    argc_,
 
   app.add_option("-f,--foreground",foreground)
     ->description("")
+    ->default_str("false")
     ->default_val(false);
   app.add_option("-d,--debug",debug)
     ->description("")